The external device polls for data from GAE. It is not specified when the data arrives. To describe it more clearly. The device is a GSM modem device that sends an SMS on the user request.
The user launches a web browser and writes a mobile phone number. The browser sends data to the GAE and the sms should be send immediately So I cannot specify how long I can wait in Thread.sleep(). You mention about Objectify. I use that library but I'm quite new to it. Does it have the mechanism that works like: process A waits for data until data into database arrives or timeout expires process B puts the data into database process a continues processing the data inserted by process B ? On Sat, Jan 29, 2011 at 3:59 PM, Didier Durand <durand.did...@gmail.com>wrote: > Hi, > > Forgot: you can use Thread.sleep() to wait (java.lang.Thread is also > part of the JRE) > > regards > > didier > > On Jan 29, 3:35 pm, Didier Durand <durand.did...@gmail.com> wrote: > > Hi, > > > > LinkedBlokingQueue is part of JRE WhiteList: > http://code.google.com/appengine/docs/java/jrewhitelist.html. So, you > > can use it. > > > > But, I dont see the need. Why don't you just from on the datastore on > > 1 side and read from it on the other. It would be very simple and rely > > on the most basic (i.e solid) mechanism of gae. (I would recommend > > Objectify for ds read/ write) > > > > As you have network round-trips, the read / write time will be > > negligible even it can seem high compared to an in-memory mechanism > > like a Queue. > > > > regards > > > > didier > > > > On Jan 29, 1:51 pm, arturad <artur.dow...@googlemail.com> wrote: > > > > > In my application an embedded device (no public IP) should connect to > > > the GAE in order to obtain some data from it. The data are provided by > > > the web browser. > > > > > The whole data-passing process looks like: > > > > > web browser -> GAE -> > > > embedded standalone device > > > > > I developed a servlet the device connects to. It issues the HTTP GET. > > > On the other side the web browser sends data using standard GWT > > > RemoteServiceServlet. > > > > > In case there is no data for the device the doGet method in the > > > servlet should stop for some seconds until user enters data or time > > > out expires. > > > > > I'm trying to use LinkedBlockingQueue to pass data between two > > > servlets. It does not work unfortunately. Seems like the GAE launches > > > new JVM for concurrent requests... I pushed the LinkedBlockingQueue > > > into memcache and get it by name from concurrent requests. Still does > > > not work. Memcache returns NOTnull. But there are no data in the > > > queue. > > > > > In order to investigate my issue I've made some tests with the > > > semaphore. Pushed the semaphore to the memcache and made some > > > concurrent operations ... -> does not work -> one process does not > > > release the other... > > > > > The problem occurs on GAE only. The whole mechanism works on the > > > development server. > > > > > Is there any way to stop/freeze one process (in the doGet method in > > > servlet) and unblock it by another one ? > > > > > Or... Is there any other way to solve my problem ? > > > Thank you for any suggestions. > > > Artur > > > > > > -- > You received this message because you are subscribed to the Google Groups > "Google App Engine for Java" group. > To post to this group, send email to > google-appengine-java@googlegroups.com. > To unsubscribe from this group, send email to > google-appengine-java+unsubscr...@googlegroups.com<google-appengine-java%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/google-appengine-java?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-java@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
